Known ink-jet print heads include a piezoelectric member, a plurality of grooves aligned in the piezoelectric member, an electrode formed on the internal surface of each of the grooves, a plurality of walls by which the grooves are separated, and a cover bonded to the walls so as to link them.
FIG. 9 is a partially cutaway perspective view of such an ink-jet print head 100. As shown in FIG. 9, the ink-jet print head 100 includes a base member 110, a frame 120 laid upon the base member 110, and an orifice plate 130 laid over this frame 120.
Actuators 111 are formed in two lines on the base member 110. Each actuator 111 includes driving elements (projections) 112 and pressure chambers 113 disposed alternately. The pressure chambers 113 are arranged so as to correspond to nozzles 131 (described later). Each driving element 112 is formed by joining together two plates made of piezoelectric zirconate titanate (PZT). These two plates are bonded such that their polarization directions are opposite to each other. The plates form a projecting shape so as to be adjacent to the pressure chambers 113 on both sides.
The base member 110 includes ink discharge apertures 114 and ink supply apertures 115 along the actuators 111. The ink discharge apertures 114 and the ink supply apertures 115 communicate with a manifold (not shown) located below the base member 110 in FIG. 9. Thereby, ink is circulated and supplied to the pressure chambers 113. That is, the pressure chambers 113 are filled with ink.
The nozzles 131 are formed in two lines in the orifice plate 130. Each nozzle 131 ejects droplets of ink through the action of the corresponding actuator 111.
FIG. 10 is an enlarged plan view of a main portion of the ink-jet print head 100. A wire 116 for transmitting a signal from a head driving integrated circuit (IC) (not shown) is connected to each driving element 112.
In such an ink-jet print head 100, a driving pulse voltage is applied to each driving element 112 from the head driving IC via the print wire 116. Consequently, a corresponding pair of left and right driving elements 112 causes shear mode deformation to curve away from each other. Subsequently, these driving elements 112 return to their initial positions, thereby applying pressure to liquid in the corresponding pressure chambers 113. Consequently, a droplet of liquid is shot forth.
However, the foregoing ink-jet print head suffers from a problem as described below. Specifically, since the ink supply apertures 114 and ink discharge apertures 115 need to be formed in the base plate 110, the base plate 110 should not be constructed from a brittle material. Taking account of external forces applied to the base material 110 during manufacture limits the choice of materials. Another problem is that the formation of a large number of apertures in the base member 110 increases manufacturing costs.
Additionally, as shown in FIG. 10, since the print wires 116 avoid the ink supply apertures 114 and the ink discharge apertures 115, the wires are disposed at narrow pitches near these ink supply apertures 114 and ink discharge apertures 115, complicating the process of manufacture.
Incidentally, if the print wires 116 are disposed at narrow pitches, carbon or other substances contained in the ink may be deposited and accumulate on the print wires 116, leading to a short circuit with the respective adjacent print wires 116.
Therefore, it is necessary to improve reliability by circulating and supplying ink to the pressure chamber without formation of ink supply and discharge apertures in the base member, thereby reducing the manufacturing costs and preventing short circuiting of the print wires.